Traditionally, polymers and commodity chemicals have been prepared from petroleum-derived feedstock. As petroleum supplies have become increasingly costly and difficult to access, interest and research has increased to develop renewable or “green” alternative materials from biologically-derived sources for chemicals that will serve as commercially acceptable alternatives to conventional, petroleum-based or -derived counterparts, or for producing the same materials as produced from fossil, non-renewable sources.
Carbohydrates or sugars are ubiquitous in agricultural materials, and hence are rational precursors for empirical innovations in the “green” materials area. Organic compounds that are readily derived from sugars include furans, robust cyclic ethers that possess structural features which can be useful for making certain polymers, pharmaceuticals, or solvents, among other industrial constituents.
A compound that has received considerable attention of late is 5-(hydroxymethyl)furfural (HMF), (Figure 1), a salient dehydration product of the abundant, inexpensive monosaccharide, fructose.
HMF is a versatile chemical antecedent to various furanic ring-based derivatives that are known intermediates for a multitude of chemical syntheses, and as plausible surrogates for aromatic hydrocarbons that derive from petroleum resources. Due to HMF's diverse functionalities, some have proposed that HMF be used to produce a wide range of commodities such as polymers, solvents, surfactants, pharmaceuticals, and plant protection agents. As alternates, derivatives of HMF are comparable to benzene-based aromatic compounds or to other compounds containing a furan or tetrahydrofuran (THF). HMF and 2,5-disubstituted furans and THF analogs, therefore, have great potential in the field of intermediate chemicals from renewable agricultural resources.
HMF itself, however, is rather unsuitable as a chemical intermediate substrate, given its propensity to decompose under thermo-oxidative conditions. Thus, one should look to derivatives of HMF for practical commercial utility. One derivative is furan-2,5-dimethanol (abbreviated as FDM, Scheme 1), which is produced from partial hydrogenation (aldehyde reduction) of HMF.
Other derivatives are 2,5-bis(hydroxymethyl)tetrahydrofuran (abbreviated as bHMTHF), saturated stereoisomeric analogs produced in a 9:1 cis (B):trans (C) diastereometic ratio when both the ring and aldehyde moieties of HMF are reduce completely (Scheme 2).
These materials can be of value as a molecular antecedent, for example, to polyesters, polyurethane foams, FDCA, plasticizers, additives, lubricants, and amphiphiles.
To become market competitive with petroleum products, however, the preparation of HMF derivatives from standard agricultural raw materials, such as sugars, need to become economically feasible in terms of cost. Heretofore, research for chemical derivatives using FDM and/or bHMTHFs has received limited attention due in part to the great cost and relative paucity (e.g., ˜$200 per gram commercially) of the compounds. Recently, a need has arisen for a way to unlock the potential of FDM and bHMTHFs and their derivative compounds, as these chemical entities have gained attention as valuable glycolic antecedents for the preparation of polymers, solvents, additives, lubricants, and plasticizers, etc. Furthermore, the inherent, immutable chirality of bHMTHFs makes these compounds useful as potential species for pharmaceutical applications or candidates in the emerging chiral auxiliary field of asymmetric organic synthesis. Given the potential uses, a cost efficient and simple process that can synthesis derivatives from FDM and/or bHMTHFs would be appreciated by manufacturers of both industrial and specialty chemicals alike as a way to better utilize biomass-derived carbon resources.